This renewal application is a continuation of the on-going Program-Project grant entitled "Cardiorespiratory Performance and Environmental Factors" expanded to include cellular and subcellular levels of function. The fundamental theme remains unchanged; e.g., the transfer of respiratory gases to and from cells with emphasis upon how this transfer is affected by changes in environmental factors such as ambient pressure, temperature, abnormal gas mixtures, exercise, and submergence in water. With the addition of new scientists and technical staff to our group we are now able to plan for a more complete program which will extend our work to the cellular effects of various environmental factors. This research will be conducted in a specially designed laboratory completed during years 01-05 of NIH support that includes an annular submergence basin, a human centrifuge, and high pressure chambers to 170 ATA for human use and higher for tissue or small animal use. An Adjacent suite of 5 laboratories has been remodelled to form a Laboratory of Cellular Physiology and scientific personnel from this group will join previous members of the current Program Project in year 06 of the renewal program. The interrelated research in gas transport is grouped in six Projects: I: Exposure to Abnormal Gaseous Environments; II: Regulatory Responses of the Ventilatory System; III: Cardiopulmonary Function in Water as an Environment; IV: Regulation of the Cardiovascular System; V: Interactions of Temperature and Acid-Base Status in Tissues, cells, and Sub-Cellular Systems; VI: Effects of Pressure on Membrane and Cellular Function.